Perovskite solar cell is currently the most promising application in photovoltaic field. In general, the formula of perovskite material is ABX₃. As shown in Figure 1, A site is monovalent cation (MA⁺, FA⁺, Cs⁺), occupying the vertex of the cube. B site is divalent metal cation (Pb²⁺, Sn²⁺), which is located at the center of cube. X site is halogen ions (Cl^-, Br^-, I^-), which is located at the face center of hexahedron. In our research, we have mastered a variety of technologies to prepare mixed ionic perovskite materials. Based on one-step method and the triple cation perovskite system, device with a PCE of 21.6% can be obtained. Based on two-step method and dual cation perovskite system, the device efficiency can reach up to 22.8%. At the same time, the efficiency of flexible perovskite solar cell can exceed 19% by selecting perovskite material and device preparation process.At present, our main research directions are defect passivation engineering, additive engineering and new carrier transport material engineering.

Figure 1. Crystal structure of the perovskite